1. Field of the Invention
The present invention relates, in general, to a system for controlling gas pressure in a dual-chamber airbag for vehicles and, more particularly, to a system for controlling gas pressure in a dual-chamber airbag for vehicles, in which upper and lower chambers of the airbag are sequentially expanded in response to collision impact and, thereafter, are controlled, separately.
2. Description of Related Art
An airbag device is a safety device, in which, when a passenger's body leans forward suddenly due to a car collision or a crashing halt, an airbag cushion expands quickly and prevents the passenger's body from directly striking a steering wheel or a dashboard, thus protecting the passenger from impact by absorbing the impact.
FIG. 4 shows an airbag cushion 10 of a conventional airbag device, which includes a cushion unit defining a single chamber therein and having a front cushion part 11 and a rear cushion part 12. The airbag cushion 10 further includes a tether 20 for maintaining a desired shape of the cushion unit in an expanded state, and a vent hole 30 for expelling gas from the cushion unit 10 after expansion so as to disperse impact applied to the passenger.
In a car collision, a collision sensor of the above-mentioned airbag device senses the collision impact and outputs a collision signal designating the collision impact to an ECU and, in response to the collision signal, the ECU determines whether it is required to actuate an inflator or not according to the collision impact designated by the collision signal. When the inflator is actuated by the ECU, the inflator burns a gas forming agent and injects a large amount of airbag gas into the airbag cushion, thus expanding the airbag cushion.
However, the above-mentioned conventional airbag device is problematic in that the airbag cushion comprises a single chamber, so that the airbag device may cause severe damage to the throat of a dummy due to relative movement between the head and the chest of the dummy caused by a difference in the weight between them in the NCAP (New Car Assessment Program) environment.
Further, in the related art, an airbag cushion having a large interior volume has been proposed. Although the airbag cushion having the large interior volume has an increased energy absorption rate and increases the dummy acceleration values, the airbag cushion is problematic in that it may compress the chest of the dummy in the NCAP environment, thus reducing the displacement values of the dummy chest.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.